Olympus MC-20+300mm with Low Light Levels – Go Slow.

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drj3 Veteran Member • Posts: 9,141
Olympus MC-20+300mm with Low Light Levels – Go Slow.
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The Olympus MC-20+300mm f4 works very well in good light. What can you do with f8 and 600mm in poor light?

I generally photograph stationary targets using A – Aperture Preferred with a minimum Low shutter speed setting of 1/40 for the 600mm f8 combination. I find this shutter speed easy to handhold without worrying about holding technique.

If that shutter speed results in too high an ISO, I switch to S – Shutter Preferred and I will drop the shutter speed to as low as 1/20. However, at such shutter speeds, I must be careful to prevent camera/lens movement induced blur. With shutter speeds below 1/20, I am much more likely to get blur, unless I am leaning against something to add stability. I will often shoot with a delayed shutter release to prevent blur produced by my shutter press when using very slow shutter speeds. For the above situations, I use CAF with single images so that I can place the focus point precisely and check focus with the DTC 2X magnification. I expect a high success rate for shutter speeds of 1/20 or faster.

However, a shutter speed of 1/20 at f8 will still result in very high ISO’s in low illumination. My solution is to shoot bursts of images, where only some of the images will be sharp. Shooting a burst, removes any movement produced by the shutter press from all but the first image. Since the burst will be at very low shutter speeds, Image Stabilization must be set to IS Priority to stabilize each image in the burst. This will result is some movement of the focus point as the camera stabilizes each image, so the technique will not work as well for a small bird surrounded by leaves/branches, but can work very well for larger targets. There is a significant reduction in frame rate as the illumination decreases and the camera stabilizes the images at slow shutter speeds.

How well does this technique work? For the first image below I used my normal single image technique (1/30). The second image was from my first test using a burst at 1/20. The dark blur on the first two images was caused by the shrubs between me and the deer. The first image shows that there will be some blur at these shutter speeds when the target moves. The deer are shedding their summer coat in preparation for winter.

The next two images are at shutter speeds of 1/10. I did over 100 exposures at this shutter speed and 43% showed no significant blur (other than some with movement of the deer’s ears or movement of some of the flies). I further dropped the shutter speed shooting bursts with shutter speeds of 1/6 and 1/5. While the percentage of sharp images decreased somewhat (the deer was more likely to move), the technique still worked quite well. I only shot a few images at 1/4 second (last deer image) since the aperture was f14 and my deer refused to remain still for a sufficient amount of time at that shutter speed to get a good estimate of success rate.

The last image of a Downy Woodpecker is an example using this technique at a shutter speed of 1/10 for a bird in a shrub. The success rate for this type of image will be very low, since the movement of the focus point caused by the sensor stabilization will prevent precise placement of the focus point on the bird, critical for a small bird (6.5 inches) from a close distance (28 feet) given the very shallow DOF.

While using a CAF burst with very slow shutter speeds will not give a high percentage of sharp images, by shooting multiple images in a very short period of time it can often allow you to get a good image in poor illumination conditions without using a tripod.

Could I get the same percentage of sharp images without using a burst? I don’t know, but the time required to shoot a single image (controlling breathing with a short shutter delay) would require the target to be stationary for a much longer period of time and thus reduce the chance that I would get any sharp images. Since I am shooting a burst (FPS 15), the target only has to remain stationary for a very short period of time to obtain usable images.

Why don’t I use a burst at faster shutter speeds? It is not possible to check for focus accuracy during a burst, the focus point moves somewhat during the burst, and the Olympus algorithm to predict focus for a moving target could cause some initial focus variability during the burst.

All images are uncropped using the Electronic shutter to prevent the deer from being frightened by the sound of the mechanical shutter.

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drj3

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